A live roller accumulator conveyor commonly includes a plurality of zones along the length of the conveyor from the infeed to the discharge end thereof, with each zone including powered rollers adapted to receive an article from an immediately upstream zone and deliver it to an immediately downstream zone. A sensor associated with each zone responds, under normal conditions, to the presence of an article stopped therein by rendering inoperative the powered rollers in the zone immediately upstream therefrom.
In this manner, articles can back up from the discharge end toward the infeed end of the conveyor when a lead article is stopped in the discharge zone. The zones are successively deadened, i.e., the powered rollers therein are successively rendered inoperative, from the discharge end to the infeed end as successive articles are stopped in successive zones upstream from the discharge end. Once the article at the discharge end is removed, the zones are reactivated to move the articles along the conveyor again. Such conveyors, wherein the zones can be activated in sequence, are shown in Vogt et al U.S. Pat. No. 4,108,303 and Vogt U.S. Pat. No. 4,109,783.
When it is desired to discharge accumulated articles from a conveyor as shown in the Vogt et al patent, each successive article must vacate the particular zone wherein it had stopped before the article stopped in the next zone upstream therefrom will begin to move. Thus although a plurality of articles may be moving at the same time, adjacent articles will be separated by a distance substantially equal to the length of a zone. The purpose of the present invention is to provide an accumulator conveyor from which accumulated articles can be discharged in groups, with minimal spacing, if any, between the adjacent articles in each group.